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Many insulation solutions are designed to protect a plant’s process piping from the risks of CUI. However, questions persist regarding the effectiveness of insulation in providing long-term CUI protection in hot, humid environments.
ROCKWOOL Technical Insulation aimed to answer these questions with an extensive testing program to evaluate the long-term durability and performance of its ProRox stone wool with CR-Tech (Corrosion Resistant Technology).
ProRox with CR-Tech features a proprietary corrosion inhibitor embedded directly into the insulation layer in contact with the pipe. When moisture is present, the inhibitor activates, forming a low-solubility protective film on the steel surface. It also buffers the water’s pH, making it less acidic and therefore less corrosive.
CR-Tech works in unison with ROCKWOOL’s proprietary WR-Tech (Water Repellent Technology), a hydrophobic solution on each stone wool fiber, to provide superior water repellency and corrosion inhibition at the same time.
Putting ProRox with CR-Tech through its paces
ROCKWOOL commissioned third-party tests to evaluate the durability of the inhibitor-treated stone wool insulation in various scenarios.
Figure 1. This ASTM G189 test setup demonstrates how water is introduced into the insulation and onto the ringed coupon surface during the water injection phase of a cycle.
The ASTM G189 test, the only industry-standard test that uses a full-scale insulated pipe to more closely simulate field conditions, was modified to simulate water exposure equal to 15 years of rainfall. Because it was prudent to select an area with significance to industrial applications and a high incidence of CUI, the annual rain totals of Houston were selected.
The ASTM G189 setup used ring-formed test coupons wrapped in different insulation types: ProRox with CR-Tech, perlite and aerogel. In the test method, water was introduced between the insulation and ringed coupon surface (Figure 1. The test replicates real-world conditions by heating the test section and exposing it to water over a set number of 24-hour cycles. Each coupon/insulation pair underwent thirty 24-hour cycles of alternating wet and dry periods, which simulates the thermal stresses that insulated pipe experiences in a plant setting.
Over the course of 30 days, the coupon/insulation pairs were exposed to a total of 7.9 liters or 2.1 gallons of water.
Under these conditions, the ringed coupon insulated with ProRox with CR-Tech had an average corrosion rate of 0.34 mils per year (MPY). Coupons insulated with aerogel had a rate of 5.64 MPY, while perlite-insulated coupons had a rate of 2.03 MPY.
Figure 2. The ASTM G189 test results showed that ringed coupons covered with ProRox with CR-Tech demonstrated a significantly lower corrosion rate compared to other insulation materials, with visible indication of corrosive damage.
Testing to the ASTM G189 has shown that ProRox with CR-Tech consistently delivers at least five times better CUI protection compared to other hydrophobic insulation materials, including those with corrosion inhibitors.
Industry implications
The findings demonstrate that embedding corrosion inhibitors into mineral wool insulation significantly improves resistance to CUI, even under prolonged water exposure and high-temperature conditions. For operators of process-intensive facilities, this approach can help extend asset life, reduce maintenance costs and improve operational safety.
As industrial infrastructure continues to expand, integrating chemical inhibition into insulation materials represents a promising direction for more reliable, long-term CUI mitigation.
Watch the video about ROCKWOOL’s testing methodology to the ASTM G189 standard.
For more information, visit rti.rockwool.com.
